Process for improving the properties of natural resins and the products obtained thereby



UNITED STATES PATEN T OFF! CE PaooEss "non IMPROVING THE rRoPER- TIES OFNATURAL RESINS AND THE rnonno'rs OBTAINED THEREBY Ernest D. Lee, Sparta,and Rupert J. Schefbauer,

Jia, Hasbrouck Heights, N. J, assignors to Interchemical Corporation,New York, N. Y., a

corporation of Ohio No Drawing. Application JlulyZ, 1949,

Serial No. 102,956

This invention relates to the process for improving thcproperties ofresinous materials obtained from resin-bearing bituminous coals, and theproducts obtained thereby.

Certain coals, notably the bituminous coal from the Utah coal fieldsobtained between Castlegate on the north and Salina Canyon on the south,contain substantial percentages, up to 10%, of resinous materialconsisting for the most part of carbon and hydrogen. Of the vari- I ousmethods that have been proposed to effect separation of the hydrocarbonresin from the coal, the one involving froth flotation, the process ofU. S. Patent 1,773,997, appears to be the most widely used. The coalresin concentrate cbtained by this technique contains 70-95% of'resin.'The resinous material is further concentrated by extracting the coalresin concentrate with suitable solvents for the resin, notablyhydrocarbon solvents such as petroleum ether, mineral spirits, "and thelike, to obtain asoluble resin of 9540070 purity.

The exact chemical structure of the complex resinous material obtainedby solvent extraction of the coa1 resin concentrate has never beenelucidated. In general appearance it is hard and friable, and is solublein ordinary hydrocarbon solvents such as petroleum ether, 'mineralspirits, and the like. Other properties, such as iodine number, acidvalue, molecular weight, 5

melting point, and the like, vary slightly, depending upon theparticular solvent usedto extract the resin. A typical resin, obtainedby extracting' the coal resin concentrate with commercial, I n-hexanecontaining less than 25% of aromatics,

has the following characteristics:

Color Dark brown Melting point (capillary) 160-'l-65 C. Acid value 6-8Iodine value (Wijs) l00-130 Specific gravity (melted) Lila-1.06Molecular weight (cryoscopic) 732 Carbon 87.10%

Hydrogen 11.17% Sulfur 0.30% Nitrogen 1 0.96%

Ash 0.45%

The solvent extracted resinous material described above is undoubtedly amixture of resins of different molecular weights and possibly differentchemical structures. When the resin obtained by extracting coalconcentrate with commercial n-hexane solvent is redissolved in 2- methylpentane to a concentration of 25' to 50% and then diluted to about 10%concentration, a high melting resin is precipitated While lower meltingresins remain in solution. High melting resins obtained in this mannerare described in the copending application of E. D. Lee and R. J.Schefbauer, Jr., Serial No. 746,857, filed May 8, 1947.

We have now discovered that new and useful. resinous products can beobtained by subjecting a solution of coal resin, or of oxidized coalresin prepared according to the method of copending U. S, patentapplication Serial No. 17,375, filed March 26, 1948, now U. S. Patent2,488,546, to treatment with an amphoteric metal halide type catalyst atan elevated temperature.

The process of the present invention is preferably carried out, whenstarting with unoxidized coal resin, by heating the finely divided coalresin spread out to a depth of approximately to inch in an oven at atemperature of 50 to 15 C. below the softening point of the resin, andthereafter treatin a solution of the resulting oxidized resin in analiphatic or aromatic hydrocarbon solvent with an amphoteric metalhalide, such as a boron trifluoride; or amphoteric metal halidecomplexes, such boron trifluoridediethyl other complex, within thetemperature range 59-65" C. Although these metal halides and metalhalide complexes are known to be good polymerization catalysts, andthere is evidence that they have a polymerizing action on coal resin, itis not known whether their sole effect is to catalyze polymerization.However, for simplicity, they will he referred to hereinafter aspolymerization catalysts.

Straight oxidation of coal resin increases the molecular weight andsolution viscosity of the resin, the effect increasing the degree ofoxidation up to a maximum of about 6-7%, based on the original weightofresin, when the completely oxidized resin becomes insoluble in ordinarypetroleum hydrocarbon solvents. Such an insolubie resin has been lessuseful. than a more soluble resin, and, therefore, coal resin ispreferably not completely oxidized. There appears to be both anoxidizing and polymerizing eifect in heating coal resin in the presenceof oxygen, as indicated by increase in molecular weight, solutionviscosity and melting point, which last has been increased by as much asabout 40 C. However, the oxidation process is difiicult to control, andproducts having reproducible solubilities and stabilities are not easilyattained. Again, reaction time is considerable.

In contrast thereto, our invention utilizing an oxidation followed by atreatment with an amphoteric metal halide type catalyst, makes possiblethe ready control of solubilities and stabilities of products havinghigh molecular weights and solution viscosities.

While an oven oxidation of divided coal resin at a temperature 515 C.below its melting point is preferred, the equivalent continuous processcan be used, in which the resin may be fed onto a horizontally movingbelt and the belt containing the resin at a desired depth can be passedthrough a heating chamber at such a rate that by the time it leaves thechamber it will have been oxidized to the desired extent.

The subsequent treatment with a polymerization catalyst is more readilyperformed after the coal resin has been oxidized. While borontrifluoride ether complex the preferred catalyst, the obvious equivalentamphoteric metal halide type catalysts may be used. Boron triiluoridegas is somewhat more reactive than its ether complex, but is notpreferred for well-known reasons.

Solutions of oxidized coal resin in aliphatic and aromatic hydrocarbonsolvents are used. As the catalytic treatment proceeds, difiieulties dueto decreased solubility make it more difiicult to manipulate solutionsin aliphatic hydrocarbon solvents, particularly with solutions greaterthan 50% concentration, as compared with aromatic hydrocarbon solventsolutions. For this reason, solution concentrations of -50% arepreferred.

Temperature of the treatment with catalyst may be varied over a widerange, f. e., -105 C. Temperatures above 90 C. decompose borontrifiuoride, while temperatures between 'l090 C. split up the borontrifiuoride ether complex when this form of catalyst is used. Theoptimum temperature range for a boron trifiuoride catalyst is 55--60 C.

The amount of catalyst used is preferably less than 1%, based on theweight of oxidized coal resin. Larger amounts may used, but as thepercentage is increased, the catalyst reactivity appears to decrease upto approximately 6%. When a boron trifluoride catalyst the optimumconcentration is approximately 0.25%.

The following examples are given to illustrate the invention.

Example 1 Finely divided coal having a melting point of l60-165 (3.,obtained by extraction crude coal "esin with commercial n-hdiane wasoxidized in an oven having a continuous conveyor for 6.7 hours at 33011, he depth of coal resin on the continuous belt being approxin'latehinch. Solutions containing 50 of the oxidized coal resin in a paraffintype etroleum hydrocarbon solvent having a dimethyl sulfate value of 2.5and a boiling range of erases C. were prepared. The oxidized resin wasthen polymerized in solution by bubbling a gas mixture of 3:1nitrogenzboron trifiuoride therethrough at a rate of 60 bubbles perminute, the solution being kept at 55-60 C. for varying time periods.Results follow:

The use of an aromatic solvent, such as toluene, has no effect on thereaction, in that it can be substituted for the solvent used above toobtain results equal to those listed above. The substitution of borontrifluoride ether complex, 48% BF3, 0.55% based on oxidized coal resinweight, gave comparable results. The catalyst is removed by addingCa(OH) 2 slurry in benzene, and filtering, and evaporating the solventby vacuum distillation to recover the resin in solid form. In this andfuture examples, viscosities were determined on 50% solutions ofpolymerized resin in the parafiinic solvent above-identified.

Example 2 Finely divided coal resin, having a melting point of 180-165C., was oxidized in trays, inch deep, in an oven at 150 C. for varyingtime periods. and thereafter polymerized in the following manner.

of oxidized coal resin was dissolved in an equal amount of the paraffmichydrocarbon solvent of Example 1, and heated to 100-105 C. Agitation wasbegun, 2.2 grams of boron trifluoride diethyl ether complex, 48% BFB,was then added, and the reaction permitted to proceed at the sametemperature for 4 hours. Then 10 grams of Ca(OI-I)z slurry in 100 gramsof benzene was added for catalyst removal after the temperature had beenreduced to 70-80 C., the reaction medium being more vigorously agitatedthereafter for 1 hour. The batch was then filtered to remove CaFz andvacuum distilled to remove benzene. Under such conditions, the followingchanges were noted:

3 hour oxidized coal resin increased in viscosit from 38.5 poises to 223poises.

4: hour oxidized coal resin increased in viscosity from 46.5 poises to970 poises.

5 hour oxidized coal resin increased in viscosity from 330 poises to4,730 poises.

6 hour oxidized coal resin increased in viscosity from 750 poises to5,500 poises.

The following changes were noted with coal resin oxidized in acontinuous conveyor heating chamber at 310 F., for varying time periods,polymerization being the same as with the oven oxidized samples.

4.6 hour oxidation: 35 poises to poises.

6.7 hour oxidation: 97 poises to 208 poises.

9.5 hour oxidation: poises to 628 poises.

10.0 hour oxidation: 240 poises to 570 poises.

Example 3 Samples of 4.6 hour 310 F. conveyor oxidized resin weresubjected to boron trifluoride diethyl ether complex according to themethod disclosed in Example 2, using increasing amounts of the borontrifiuoride ether complex catalyst, which contains 4.8% BFs, with thefollowing results:

Viscosity After Polymerization, Poises Per Cent BF Resin Basis Example 4When 6.7 hour 330 F. conveyor oxidized coal resin was treated accordingto the method disclosed in Example 1 for 4 hours at a temperature of55-60 C. using a BF: gas rate of 60 bubbles per minute at an influxratio of nitrogen to 313's of 3:1, viscosities of the order of 900 to990 poises were obtained with the finished resins. Viscosities of thesame order are obtained when the ether complex of 1315's is used undercomparable conditions.

Example 5 Crude coal resin was extracted with commercial n-hexane, andthe purified recovered coal resin, having a melting point of l60-165(3., dissolved in paraifinic hydrocarbon solvent, previously identified,to form a 50% solution. Using the BE gas rate and make-up of Example 4for 4 hours at 55-60 C., the coal resin Was polymerized to yield aproduct having a solution viscosity of 50 poises, compared with 25poises for the unreacted coal resin. Doubling the flow of BFs gascatalyst and increasing the polymerization temperature to 75-80 C. gavea, product having a solution viscosity of 86 poises. The prior reactedresin had a melting point of l78183 C., while the latter had a meltingpoint of 180-185 0., compared with a melting point of 160-l65 C. for thestarting resin.

Example 6 A 50% solution of 6.7 hour 150 C. conveyor oxidized coal resinin toluene was treated with 2.2%, based on the oxidized coal resin, ofboron trifluoride dietherate catalyst with stirring, and heat applieduntil a temperature of 100 C. was reached. The temperature of thereaction medium was held at 100 C. for 4 hours with stirring, thenreduced gradually to 80 C. A slurry of 6 Ca(OH) 2 in toluene, 10% of theweight of oxidized coal resin, was added, and the resin solutionconcentration reduced to 40% with additional toluene. Rapid stirring wascontinued for to 1 hour, the hatch was then aerated for removal ofether, then centrifuged to eliminate CaFz. The toluene was distilled offunder vacuum and the resin dried at low temperature. The recovered resinhad the following properties: M. P. 195- 225 C., iodine value 79.6,solution viscosity 2,030

poises. This compares with the following corresponding values forn-hexane extracted coal resin: M. P. 160-165 C., iodine value 130, andsolution viscosity 25 poises.

The modified resins prepared according to this invention are useful inprinting inks, protective and decorative coatings, and the like.

We claim:

1. Method for improving the properties of a resin derived fromresin-bearing coal of the Utah type, which comprises subjecting asolution of the resin to the action of an amphoteric metal halide typecatalyst at an elevated temperature.

2. Method for improving the properties of a resin derived fromresin-bearing coal of the Utah type, which comprises subjecting saidresin to an oxygen containing gas at an elevated temperature at least 5C. below the softening point of the resin, and thereafter subjecting asolution of the oxidized resin to the action of an amphoteric metalhalide type catalyst at an elevated temperature.

3. Method of claim 1, in which the catalyst is boron trifluoride gas.

4. Method of claim 2, in which the catalytic reaction temperature is -60C.

5. Method of claim 2, in which the catalyst is a boron trifiuoridecatalyst.

6. Method of claim 2, in which the oxidation step temperature is 5-15 C.below the softening point of the resin, and the catalytic reactiontemperature is 55-60 C. with a boron trifiuoride catalyst.

7. Polymerized coal resin of the Utah type.

t 8. Polymerized oxidized coal resin of the Utah 9. As a new product, aresin of the group consisting of polymerized coal resin of the Utah typeand polymerized oxidized coal resin of the Utah type.

ERNEST D. LEE. RUPERT J. SCHEFBAUER, JR.

N 0 references cited.

1. METHOD FOR IMPROVING THE PROPERTIES OF A RESIN DERIVED FROMRESIN-BEARING COAL OF THE UTAH TYPE, WHICH COMPRISES SUBJECTING ASOLUTION OF THE RESIN TO THE ACTION OF AN AMPHOTERIC METAL HALIDE TYPECATALYST AT AN ELEVATED TEMPERATURE.
 9. AS A NEW PRODUCT, A RESIN OF THEGROUP CONSISTING OF POLYMERIZED COAL RESIN OF THE UTAH TYPE ANDPOLYMERIZED OXIDIZED COAL RESIN OF THE UTAH TYPE.